The present invention relates to a refrigeration compressor having an oil filter. In particular, the present invention is directed to the placement of the oil filter within the body of the compressor.
A refrigeration compressor is an integral part of a refrigeration unit, along with an evaporator, expansion valve, and condenser. A compressor compresses the refrigerant, thus raising its temperature. This compressed refrigerant gas then enters the condenser and is condensed into liquid form by contacting it with another cooler medium, such as ambient air, ground water, or water from a cooling tower loop. After the heat is removed from the refrigerant in the condenser, the condensed refrigerant liquid goes to an expansion valve. The expansion valve allows a limited quantity of liquid refrigerant to enter the evaporator, while maintaining the pressure difference between the condenser (at higher pressure) and the evaporator (at lower pressure). The liquid refrigerant entering the evaporator evaporates after contacting a heat load, such as the refrigerator interior or ventilation air that is to be cooled, thus absorbing heat from the heat load. The refrigerant vapor leaves the evaporator and returns to the compressor to repeat the cycle.
A refrigeration compressor commonly has a cast metal housing and a need for lubrication of the moving parts, such as the gears and bearings. A refrigeration compressor contains an oil sump where lubricating oil collects and a lubrication system to direct oil from the sump to each lubrication point. The oil lubrication system has an oil filter for removing particulate matter from lubrication oil.
The oil filter associated with a refrigeration compressor has been provided in a separate pressure vessel attached onto the outside of the compressor, or even contained in a separate pressure vessel unattached to the compressor body.
Having a separate pressure vessel increases the potential for oil leaks. In addition, an oil filter attached to the housing of a compressor is not easily replaced. In many refrigeration compressors in the prior art it is quite difficult to replace the oil filter without losing the charge of refrigerant. Another problem with prior art refrigeration compressors and their separate oil filters is that the oil filter element itself gets contaminated quite easily, and this greatly reduces its filtering efficiency. External oil filters also make it more difficult for clean, filtered oil to reach the lubrication points, since the oil has to travel farther (and thus pick up more impurities) to get to its targets. In addition, an oil filter vessel projecting from the compressor is exposed and subject to injury, particularly when the compressor is being shipped and installed.
U.S. Pat. No. 5,159,820 discloses an oil separator integrally mounted on a compressor. In this patent, elements that separate the refrigerant from the oil and then filter the oil are attached to the compressor casting and operatively connected to the compressor. This reference, however, does not disclose an oil filter located inside of the compressor casting.
An object of the invention is to provide an oil filtration system having fewer leak points.
A further object of the invention is to enable the filter element to be replaced while the compressor is charged with refrigerant.
Another object of the invention is to allow cleaner oil to reach the lubrication points in the compressor.
Still another object of the invention is to provide an oil filter which does not project outward from the compressor.
To achieve at least one of the objects at least in part, and in accordance with the purpose of the invention, as embodied and broadly described herein, the refrigeration compressor of the present invention includes a cast member and a cavity formed in that cast member. The cavity is divided into an inlet cavity and outlet cavity by a filter element. The compressor also includes an inlet port for directing unfiltered oil into the inlet cavity and an outlet port for directing clean oil away from the outlet cavity.
Two advantages of this invention are that the possibility of oil leaks is reduced and cleaner oil reaches the lubrication points in the compressor. A further advantage of this internal oil filter is to allow easy replacement of the inexpensive filter element (as opposed to the whole oil filter vessel) while the compressor is charged with refrigerant. A further advantage of this invention is to minimize the possibility that the filter vessel will be damaged during shipping or installation of the compressor.
Additional objects and advantages of the invention will be set forth in part in the description that follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims.
The present invention provides a refrigeration compressor. The compressor comprises a cast member with a cavity formed in the cast member. An oil filter element divides the cavity into an inlet cavity and an outlet cavity. The cavity includes an inlet port for directing oil to be filtered into the inlet cavity, and an outlet port for directing filtered oil out of the outlet cavity.
The present invention also provides a gear driven refrigerant compressor. The compressor comprises: a housing; a low speed drive shaft with an integrally mounted bull gear; and a pinion drive shaft with a pinion drive gear engaging the bull gear, all located in an upper region of the housing. The compressor also includes an oil sump located in a lower region of the housing; and an oil filter cavity formed in an intermediate region of the housing between the upper region and the lower region, the cavity containing an oil filter.
The present invention further provides that the oil filter include at least one end cap having eared elements where the eared elements act as a spacer between the cavity and the oil filter.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description, serve to explain the principles of the invention.